Re: [PATCH v5 2/3] KVM: x86/ioapic: Implement support for I/O APIC version 0x20 with EOIR

[David Woodhouse]

On Mon, 2025-12-29 at 15:57 +0000, Khushit Shah wrote:
> 
> 
> We can't use `_respect_` here because in QUIRKED mode with in-kernel IRQCHIP:
> 
>   advertise = false  (version 0x11 advertised, no EOIR register)
>   respect   = true   (legacy quirk: honor SPIV bit even if not advertised)

Oh wow, right. Since commit 0bcc3fb95b97a ("KVM: lapic: stop
advertising DIRECTED_EOI when in-kernel IOAPIC is in use"), KVM with
the in-kernel I/O APIC will *not* advertise the EOI suppression in the
local APIC version register… but does actually honour the DIRECTED_EOI
bit if the guest sets it anyway.

While with a userspace I/O APIC, KVM *will* advertise it, but not
honour it.

Yay.

So yes, your code is the best way to do it. Sorry for the noise.

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